TITANIUM DIOXIDE CATALYST STRUCTURE FOR PROCESSES UP TO 1000 °C AND THE MANUFACTURING THEREOF

Description

Technical field

[0001] The invention relates to a TiO₂ catalyst structure suitable for catalytic processes at the temperature up to 1000°C.

Background of the Invention

[0002] More efficient novel catalyst structures and catalyst support structures for heterogeneous catalysis are more and more meaningful considering the growing energy cost. The composition of the active substance is essential for the efficiency of catalyst structure, but its surface area and accessibility of the surface are also important. It is not easy to secure these two properties. Except for the final macro-shape, which is created for instance by pelletization, it is the inner structure, its porosity and the geometrical configuration of particles that have an impact on the surface accessibility.

[0003] The choice of the proper catalyst support structure often plays a crucial role especially in the case where the creation of a chemical bond between the carrier and the catalyst is necessary. For example this is the case in the system of SiO₂ or TiO₂ (supporting structure) and MoO₃ (catalyst).

[0004] The synthesis problems and the thermal resistance of the catalyst structure are often important factors limiting its usability. The preparation or application of a catalyst often requires relatively high temperatures at which the structure can sinter, densify, lose the specific surface area, moreover an undesirable chemical reaction between the catalyst support structure and the catalyst can occur.

[0005] The TiO₂ nano-particles in the hydrated or anatase form are especially sensitive to the thermal cycles exceeding 300°C.

[0006] EP 0782971 A1 describes a process for manufacturing extra large particles of anatase pigment. The calcination process occurs above 1000°C. The received anatase titanium dioxide has a large average particle size (0.2 - 0.3 microns = 200 - 300 nanometers).

[0007] US 2003/0181329 Tanaka Jun describes a low-temperature hydrothermal method delivering composite particles of the photocatalytic TiO₂ and a compound inactive as a photocatalyst. TiO₂ is in the rutile, brookite or anatase form, while the compound is selected from a group consisting of Si, Al, P, S and N compounds, wherein the said compound exists partially on a surface of titanium dioxide, increasing its overall photocatalytic activity.

[0008] The step of preparing water based slurry comprising titanium dioxide includes a process for wet synthesis of titanium dioxide.

[0009] WO 2007/024917 A2 describes highly photocatalytic phosphorus doped nano anatase-TiO₂ and the manufacturing method thereof.

[0010] The spray pyrolysis process providing phosphorus doped nano anatase-TiO₂ with several times higher photocatalytic activity compared to an undoped anatase comprises steps of:

1) spray drying of a phosphorus-doped solution of titanium oxychloride, titanium oxysulphate or aqueous solution of another titanium salt to produce an amorphous titanium dioxide solid intermediate with homogeneously distributed atoms of phosphorus through the matter,

2) calcining the amorphous, solid intermediate at a temperature between 300 and 900 °C. The particles were organized in a hollow sphere thin film macrostructure (all examples).

[0011] The phosphorus doping is used to increase the photocatalytic activity of TiO₂. Despite the attractiveness of the TiO₂ anatase catalyst structures, their preparation using the sulfate process, i.e. hydrolysis of TiOSO₄ creating the titanium hydrate of the composition approximately Ti(OH)₄, which is consecutively calcined, has serious drawbacks, such as the poor heat resistance accompanied by the fast loss of the specific surface area during the heat exposure and finally the crystal phase transformation into rutile. Materials prepared by the sulphate process often show a high content of residual hydrate and sulphur, which don't disappear even at temperatures exceeding 450°C.

Summary of the Invention

[0012] The TiO₂ catalyst structure according to claim 1 for the catalytic processes at the temperature up to 800°C eliminates the mentioned disadvantages. It consists of TiO₂ nano-particles in the anatase crystal form, doped with phosphorus in the range of 0.05 to 5 wt % P on the TiO₂ basis. The nano-particles are organized into the planar circular aggregates, which specific surface area varies from 40 to 120 m²/g. The TiO₂ catalyst structure consisting of TiO₂ nano-particles is made by drying and calcination of the intermediate product in the temperature range from 350 to 900°C, preferably at 450 to 800°C for 1 to 24 hours. The intermediate product is made by addition a phosphorus compound corresponding to 0.05 to 5 wt % of a phosphorus on the TiO₂ basis to the titanium hydrate paste prepared by hydrolysis of titanium oxysulphate.

[0013] The TiO₂ catalyst structure according to claim 3 for the catalytic processes at the temperature up to 1000°C consists of TiO₂ nano-particles in the crystalline form of anatase, doped with 0.05 to 5 wt % of phosphorus on the TiO₂ basis, with the morphology of aggregated compact particles with the specific surface area 20 to 40 m²/g. The nano-particles of anatase are made by drying and calcination of the intermediate product in the temperature range from 500 to 1000°C for 1 to 24 hours. The intermediate product is made by addition a phosphorus compound corresponding to 0.05 to 5 wt % of a phosphorus on the TiO₂ basis to the titanium hydrate paste prepared by hydrolysis of titanium oxysulphate.

[0014] The catalyst structure of TiO₂ for the catalytic processes at the temperature up to 800°C or up to 1000°C preferably consists of TiO₂ nano-particles in the anatase crystal form, doped with 0.55 to 5 wt % of phosphorus on the TiO₂ basis.

[0015] The use of the TiO₂ catalyst structure is convenient for many catalytic processes, where according to the invention, the active substances selected from the group consisting of silver, copper, gold, platinum metals, nickel, molybdenum and metal oxides with the exception of alkaline metal oxides are deposited on the surface of the TiO₂ structure.

[0016] The manufacturing method of the catalyst structure for processes at the temperature up to 800°C is based on the addition of phosphorus compound in the amount of 0,05 to 5 wt % of phosphorus on the TiO₂ basis to the titanum hydrate paste, prepared by the hydrolysis of titanum oxysulphate. The intermediate product is dried and consequently calcined at the temperature 350 to 900°C, preferably at 450 to 800°C for the period of time from 1 to 24 hours. The obtained catalyst structure is in the form of powder.

[0017] The manufacturing method of the catalyst structure for processes at the temperature up to 1000°C is based on the addition of phosphorus compound in the amount of 0,05 to 5 wt % of phosphorus on the TiO₂ basis to the titanum hydrate paste, prepared by the hydrolysis of titanum oxysulphate. The intermediate product is dried and consequently calcined at the temperature 500 to 1000°C, preferably at 450 to 800°C for the period of time from 1 to 24 hours. The obtained catalyst structure is in the form of powder.

[0018] The phosphorus compound is selected from the group of substances consisting of phosphoric acid and water-soluble phosphates.

[0019] It is convenient to apply the active substances onto the powder of this TiO₂ catalyst structure.

[0020] It is possible to process the obtained powder of the catalyst structures, possibly with the active substances, into the shape required for catalysis by pressing, granulation, pelletization, flaking, micronizing or by another common technique.

[0021] The catalyst structures consisting of the circular, planar aggregates of TiO₂ nanoparticles in the anatase form, with the specific surface 40 to 120 m²/g can be used for the long - term applications at the temperature up to 800°C.

[0022] The catalyst structures consisting of the aggregates of compact TiO₂ nanoparticles in the anatase form, with the specific surface 20 to 40 m²/g can be used for the short - term applications at the temperature up to 1000°C.

[0023] The catalyst structures can be conveniently used for the catalytic destruction of nitrogen oxides NO_x from the diesel aggregates and exhaust gasses. They can also be used for the photocatalytic applications or as a catalyst support structure for the active substances selected from the group consisting of silver, copper, gold, platinum metals, nickel, molybdenum and metal oxides with the exception of alkaline metals oxides.

[0024] The catalyst structures are in the crystal phase of anatase. The anatase nanoparticles are organized in roughly circular planar formations. The circular planar formations consist of individual nanoparticles which size varies typically from 5 to 25 nanometers. The average radius size of planar circular unit, on which the nanoparticles are organized, is usually 30 - 50 nanometers and its thickness varies from 5 to 25 nanometers (it corresponds to the size of the individual anatase nanoparticles). Some of the units are interconnected forming larger units with the size up to 100 nanometers. Thanks to its morphology, the mentioned planar nano-anatase structure possess very high specific surface area, high porosity, excellent accessibility of the surface and significantly higher thermal stability than the undoped TiO₂.

[0025] The organization of nanoparticles aggregated into the planar circular structure was surprisingly discovered when a small amount of phosphorus was added as a dopant to the paste of titanum hydrate which was consequently calcined. Whereas the undoped material simply fuses into large aggregates creating a mixture of nanoparticles with a low specific surface area, broad particle size distribution and without any signs of an organization into a planar circular substructure, the doped material is organized in the circular planar units after the calcination at the same temperature.

[0026] Moreover the addition of phosphorus evidently stabilizes the crystalline phase of anatase and shifts its thermal transformation into the rutile up to higher temperatures.

[0027] It was experimentally proven that this structure forms during the thermal processing of phosphorus doped titanum hydrate Ti(OH)₄ at the temperatures above 350°C. The titanium hydrate is made from the titanium oxysulphate TiOSO₄ precursor. The specific surface area of the titanium hydrate paste which is the input material for the reaction typically varies from 200 to 350 m²/g.

[0028] The exact reason is not known; however, using of the titanium hydrate prepared differently, for instance by the hydrolysis of titanium oxychloride, in combination with the phosphorus doping, doesn't produce the morphology of aggregates organized in the planar circles.

[0029] The stages of the formation, existence and transformation of the circular planar morphology of the aggregates are schematically depicted in the Figure 1. Figure 2A shows a SEM photograph of the mentioned aggregates suggestive of little flat rings. Figure 2B captures the transformation of the circular planar aggregates into the compact nano-particles of anatase with the average individual particle size corresponding approximately to the original size of the radius of the circular planar structure. From the figures 2A and 2B it is obvious that the change of morphology is accompanied by a significant decrease of the specific surface area of the nano-anatase product. The temperature at which the planar circular structure transforms into the morphology of compact particles is specific for the particular content of phosphorus. The phosphorus concentration stabilizes the circular morphology at high temperatures, at which the undoped material completely sinters, loses the specific surface area or even changes the crystal phase.

[0030] To create the planar circular nano-anatase structure, it is convenient using the phosphorus level in the range from 0.05 to 5 wt % with the optimal phosphorus level from 0.1 to 1 wt % on the TiO₂ basis.

[0031] If the amount of phosphorus is zero, the particles spontaneously fuse together and a broad particle size distribution is created as early as the hydrate converts into the oxide. Without phosphorus the organized planar circular morphology is not created.

[0032] At the low content of phosphorus between 0.05 - 0.1 wt % on the TiO₂ basis, the planar circular structure of nano-anatase aggregates is stable approximately in the temperature range from 500 to 600°C.

[0033] Another increase of the phosphorus content to 1 to 5 wt % on the TiO₂ basis shifts the temperature of transformation of the circular planar structure higher to 650 to 800°C.

[0034] If we increase the calcination temperature approximately by another 100 to 250°C higher, another change of morphology occurs due to the intensive fusion of particles into the large, hard-fused aggregates, similar to these in the undoped product. We will see a collapse of the specific surface area and creation of the broad particle size distribution. The typical product of this fusion is shown in the Figure 3. The hard-sintered particles of anatase are mostly outside the nanosize range. The specific surface of the fused products is typically below 20m²/g, most frequently from 5 to 15 m²/g. Despite its disadvantages it is this type of hard-sintered products, which is now used for the catalyst structures for variety of syntheses in the industry.

[0035] The manufacturing of the above mentioned products with the planar circular nano-anatase structure is based on the preparation of titanium hydrate Ti(OH)₄ paste via hydrolysis of titanium oxysulphate TiOSO₄, addition of a compound containing phosphorus, drying the doped paste and consequential calcination in the temperature range from 350°C to 900°C for the period of time from 1 to 24 hours.

[0036] In the case of preparing the titanium oxysulphate from an ore already containing phosphorus, for example ilmenite, the amount of phosphorus is just brought to the required level with the appropriate quantity of the phosphorus compound.

[0037] The further increase of the calcination temperature by 100°C to 200°C produces the porous structures consisting of compact nano-particles of anatase, created by the fusion of the planar circular aggregates. These structures have an outstanding thermal stability and still possess relatively high specific surface area. Phosphoric acid or a phosphate, soluble in water, can be conveniently used for doping the titanium hydrate paste. The flow sheet diagram of manufacture is shown in the Figure 7.

[0038] Even though the morphology of planar circular aggregates with the significantly higher accessibility of the surface is optimal for use as a catalyst, the structure of compact nano-particles of anatase, created from the circular structure, is also usable. This concerns especially applications, where the catalyst is exposed to the long-term high temperatures up to 850°C and requires the ability to resist short-term temperatures as high as 1000°C without a significant loss of the specific surface area.

[0039] The specific surface area of the materials with the morphology of circular planar aggregates is usually well above 40m²/g. It typically ranges from 50 to 120m²/g (the specific surface area is determined from the adsorption isotherms of nitrogen at 77K and is referred to as BET). The important characteristic of this morphology is the high specific surface area and also good accessibility of the surface.

[0040] The materials with the structure of compact particles, created from the circular aggregates, usually have the specific surface area higher than 20m²/g, and frequently it varies from 25 to 35m²/g. These materials show a low content of sulfur, which is convenient for functioning as a catalyst structure. From the viewpoint of its use as a catalyst structure, this morphology has high enough and accessible surface (Figure 6). Fifty percent of the TiO₂ surface is typically lost in the connections between sintered particles contrary to the planar circular structure where the TiO₂ open (accessible) surface is tens of percent higher.

[0041] Very high loss of the specific surface area is typical for the third phase of the fusion. It usually drops down under 15m²/g. Also the degree of sintered particles, where the ratio of the open TiO₂ surface to the surface used by sintered connections between the particles drops down (Figure 3). The further heat treatment above this limit results in the TiO₂ crystal phase transformation from anatase into rutile.

[0042] The open morphology of these products is convenient for deposition of the active substances on the TiO₂ surface such as platinum and platinum metals, nickel, cobalt, silver, copper, gold and metal oxides except for alkaline metal oxides. For example, water solution of ions of these active substances can be used to prepare a suspension with the TiO₂ catalyst structure, which is further dried e.g. in a spray dryer and eventually calcined. Thanks to the open morphology and accessibility of the surface, a suspension of circular planar catalyst structure is convenient for the deposition of the active substances by variety of methods such as precipitation, complexing, gas phase vapor deposition, or thermal decomposition on the surface of the TiO₂ structure, and similar.

[0043] The products manufactured by the described method show a high photocatalytic activity. They can be conveniently used not only as a catalyst structure but also as a photocatalyst.

[0044] The described intermediate products can be directly used in the form of loose powder or they can be further processed into the desired form by micronization, pressing, granulation, milling or other processes typical for making catalysts.

Description of the drawings

[0045] 

Figure 1 shows schematically the process of formation of the TiO₂ nano-anatase circular planar aggregates from the titanium hydrate, an interval of their existence and alteration of their morphology into the compact particles during elevation of the calcination temperature. The diameter of the circle mark is 30 nm.

Figure 2 shows electron scanning microscope (SEM) micrographs on the same scale:

A) Nanoparticles TiO₂ - anatase organized in the circular planar aggregates, typically from 20 to 50 nm in size

B) The compact nanoparticles of TiO₂ - anatase created by heating the circular planar aggregates above 800°C. The typical size of the created compact particles typically varies from 20 to 50nm and correlates roughly to the diameter of the original planar aggregates before the fusion.

Figure 3 shows a scanning electron microscope (SEM) photograph of the fused nano-anatase doped with phosphorus after the calcination at the temperature above 900°C.

Figure 4 shows a SEM photograph which depicts the circular planar structure of nano-anatase prepared according to example 1.

Figure 5 shows a SEM photograph which depicts the circular planar structure of nano - anatase prepared according to example 2.

Figure 6 shows a SEM photograph which depicts the structure of nano-anatase compact particles prepared according to example 3.

Figure 7 shows a flowchart of the production process of the nano-anatase circular planar structure and the following processing into the specific products.

Examples

[0046] The following examples illustrate but do not limit the presented invention.

Example 1.

[0047] A concentrated solution of titanium oxysulphate TiOSO₄ was hydrolyzed by addition of hot water and by bubbling hot water vapor through the solution. Titanium hydrate of an approximate composition Ti(OH)₄ was obtained and separated from the sulphuric acid solution by sedimentation and filtration. The amount of 1% phosphoric acid corresponding to 1 wt% of phosphorus in TiO₂ was added to the filtered titanium hydrate paste. The suspension was properly mixed and after that it was dried at the temperature 150°C. The dry intermediate product was further calcined at the temperature 600°C for 10 hours. The obtained product was a soft white powder with the specific surface area (BET) 77m²/g. The average particle size 9 nm was determined from the roentgen diffraction (XRD) and calculated using the Scherrer's equation. The particle size and the circular planar morphology of this product are noticeable from Figure 4. The sample shows high photocatalytic activity. If 1wt% AgNO₃ solution is applied to the TiO₂ surface, silver rapidly develops on it, showing one of the ways of applying the active substance for catalysis onto the TiO₂ structure. This structure is stable at the temperature up to 750°C.

Example 2.

[0048] An amount of 0.5% phosphoric acid corresponding to 0.5 wt% of phosphorus in TiO₂ was added to the titanium hydrate paste, created by the hydrolysis of TiOSO₄. The suspension was properly mixed and after that it was dried at the temperature 150°C. The dry intermediate product was further calcined at temperature 650°C for 10 hours. The obtained product is a soft white powder with specific surface area (BET) 50m²/g and 22nm particle size that was determined from roentgen diffraction and calculated using the Scherrer's equation. The product consists of relatively large nano-particles and possesses the circular morphology, which is noticeable in Figure 5.

Example 3.

[0049] The amount of 0.1% phosphoric acid corresponding to 0.1 wt% of phosphorus in TiO₂, was added to the titanium hydrate paste. The suspension was properly mixed and after that it was dried at the temperature 150°C. The dry intermediate product was further calcined at 700°C for 10 hrs. The obtained product is a soft white powder with the specific surface area (BET) 30m²/g. The average particle size 30nm was determined from roentgen diffraction and calculated using the Scherrer's equation. The created material shows the morphology of compact particles, as it is noticeable in Figure 6. For comparison, materials doped with 1 to 5 wt % of phosphorus were calcinated in parallel. They still show the circular planar morphology of aggregates with the double specific surface area compared to the material described above.

Industrial utilization

[0050] The catalyst structures described in this invention have significantly larger and more accessible surface, high thermal resistance, phase purity of anatase and show easier processing of the powder than the undoped TiO₂. These nano-structures are a good substitution of the materials which are industrially used today as the catalyst structures.There we can expect an improvement of the process effectiveness. The nano-anatase catalyst structures are suitable for applications which require a high thermal resistance. The thermal resistance of these structures significantly widens the use of TiO₂ in processes for degradation of nitrogen oxides NO_x from diesel aggregates and exhaust gasses. It is also convenient to use the structures created by this method for photocatalysis.

Claims

1. A TiO₂ catalyst structure for the catalytic processes at the temperatures up to 800°C in a form of powder consisting of TiO₂ nano-particles in the anatase crystal form doped with phosphorus, wherein the content of phosphorus is 0.05 to 5 wt% on the TiO₂ basis, and the nano-particles in the anatase crystal form are organized into the circular planar aggregates with the specific surface area from 40 to 120 m²/g, wherein the TiO₂ catalyst structure consisting of TiO₂ nano-particles is made by drying and calcination of the intermediate product in the temperature range from 350 to 900°C for 1 to 24 hours, wherein the intermediate product is made by addition a phosphorus compound corresponding to 0.05 to 5 wt % of a phosphorus on the TiO₂ basis to the titanium hydrate paste prepared by hydrolysis of titanium oxysulphate.

2. The TiO₂ catalyst structure for the catalytic processes at the temperatures up to 800°C, according to the claim 1, consisting of TiO₂ nano-particles made by drying and calcination of the intermediate product in the temperature range from 450 to 800°C for 1 to 24 hours.

3. A TiO₂ catalyst structure for the catalytic processes at the temperatures up to 1000°C in a form of powder consisting of TiO₂ nano-particles in the anatase crystal form doped with phosphorus, wherein the content of phosphorus is 0.05 to 5 wt% on the TiO₂ basis, and the nano-particles in the anatase crystal form with the morphology of aggregated compact particles with the specific surface area from 20 to 40 m²/g, wherein the TiO₂ catalyst structure consisting of TiO₂ nano-particles is made by drying and calcination of the intermediate product in the temperature range from 500 to 1000°C for 1 to 24 hours, wherein the intermediate product is made by addition a phosphorus compound corresponding to 0.05 to 5 wt % of a phosphorus on the TiO₂ basis to the titanium hydrate paste prepared by hydrolysis of titanium oxysulphate.

4. The TiO₂ catalyst structure according to any one of claims 1 to 3, consisting of TiO₂ nano-particles in the crystal form of anatase, doped with 0.55 to 5 % weight amount of phosphorus on the TiO₂ basis.

5. The TiO₂ catalyst structure for the catalytic processes according to one of claims 1 to 3, wherein the phosphorus compound is selected from the group consisting of phosphoric acid and water soluble phosphates.

6. The TiO₂ catalyst structure for the catalytic processes according to any one of claims 1 to 3, wherein active substances are applied to the surface of the TiO₂ catalyst structure.

7. The TiO₂ catalyst structure for the catalytic processes according to claim 6 wherein the active substances are selected from the group consisting of silver, copper, gold, platinum metals, nickel, molybdenum and metal oxides with the exception of alkaline metals oxides.

8. A method of manufacturing the TiO₂ catalyst structure for the catalytic processes according to claim 1 or 2, comprising:

preparing a titanium hydrate paste by hydrolysis of titanium oxysulphate;

adding a phosphorus compound in an amount corresponding to 0.05 to 5 wt% on a TiO₂ basis, to obtain an intermediate product; and

drying and subsequently calcining the intermediate product for 1 to 24 hours in the temperature range of 350°C to 900°C or 450°C to 800°C.

9. A method of manufacturing the TiO₂ catalyst structure for catalytic processes according to claim 3, comprising:

preparing a titanium hydrate paste by hydrolysis of titanium oxysulphate;

adding a phosphorus compound in an amount corresponding to 0.05 to 5 wt% on a TiO₂ basis, to obtain an intermediate product; and

drying and subsequently calcining the intermediate product for 1 to 24 hours in, the temperature range of 500°C to 1000°C.

10. The method of claim 8 or 9, wherein the phosphorus compound is selected from the group consisting of phosphoric acid and water soluble phosphates.

11. The method of one of claims 8 to 10, wherein active substances are applied onto the surface of the TiO₂ catalyst structure.

12. The method of one of claims 8 to 11, wherein a powder of the obtained TiO₂ catalyst structure, or the catalyst structure with the active substances, is further processed into the required shape by pressing, granulation, pelletization, flaking, micronizing or by another common technique.

13. Use of the TiO₂ catalyst structure according to any one of claims 1, 2 and 6 for long-term applications at the temperatures up to 800°C.

14. Use of the TiO₂ catalyst structure according to the claims 3 or 6 only for short-term applications at the temperatures up to 1000°C.

15. The use according to claim 13 or 14, for the catalytic decomposition of nitrogen oxides NOx from diesel aggregates and exhaust gases.

16. Use of the TiO₂ catalyst structure according to any one of claims 1 to 7 for photocatalytic applications.

Ansprüche

1. TiO₂-Katalysatorstruktur für katalytische Prozesse bei Temperaturen bis zu 800°C in Form eines Pulvers, das aus TiO₂-Nanopartikeln in der Anatas-Kristallform besteht, dotiert mit Phosphor, wobei der Phosphorgehalt 0,05 bis 5 Gew.-% auf TiO₂-Basis beträgt, und die Nanopartikel in der Anatas-Kristallform in kreisförmig-planaren Aggregaten organisiert sind, deren spezifische Oberfläche von 40 bis 120 m²/g beträgt, wobei die aus TiO₂-Nanopartikeln bestehende TiO₂-Katalysatorstruktur durch Trocknen und Kalzinieren eines Zwischenprodukts im Temperaturbereich von 350 bis 900°C für 1 bis 24 Stunden hergestellt ist, wobei das Zwischenprodukt durch Zufügen einer Phosphorverbindung entsprechend 0,05 bis 5 Gew.-% Phosphor auf TiO₂-Basis zu einer durch Hydrolyse von Titanoxysulfat hergestellen Titanhydrat-Paste hergestellt ist.

2. TiO₂-Katalysatorstruktur für katalytische Prozesse bei Temperaturen bis zu 800°C gemäß Anspruch 1, bestehend aus durch Trocknen und Kalzinieren des Zwischenprodukts im Temperaturbereich von 450 bis 800°C für 1 bis 24 Stunden hergestellten TiO₂-Nanopartikeln.

3. TiO₂-Katalysatorstruktur für katalytische Prozesse bei Temperaturen bis zu 1000°C in Form eines Pulvers, das aus TiO₂-Nanopartikeln in der Anatas-Kristallform besteht, dotiert mit Phosphor, wobei der Phosphorgehalt 0,05 bis 5 Gew.-% auf TiO₂-Basis beträgt, und die Nanopartikel die Morphologie von aggregierten kompakten Partikeln mit einer spezifischen Oberfläche von 20 bis 40 m²/g aufweist, wobei die aus TiO₂-Nanopartikeln bestehende TiO₂-Katalysatorstruktur durch Trocknen und Kalzinieren eines Zwischenprodukts im Temperaturbereich von 500 bis 1000°C für 1 bis 24 Stunden hergestellt ist, wobei das Zwischenprodukt durch Zufügen einer Phosphorverbindung entsprechend 0,05 bis 5 Gew.-% Phosphor auf TiO₂-Basis zu einer durch Hydrolyse von Titanoxysulfat hergestellen Titanhydrat-Paste hergestellt ist.

4. TiO₂-Katalysatorstruktur gemäß einem der Ansprüche 1 bis 3, bestehend aus TiO₂-Nanopartikeln in der Anatas-Kristallform, dotiert mit 0,55 bis 5 Gewichts-% Phosphorgehalt auf TiO₂-Basis.

5. TiO₂-Katalysatorstruktur für katalytische Prozesse gemäß einem der Ansprüche 1 bis 3, wobei die Phosphorverbindung ausgewählt ist aus der Gruppe, die aus Phosphorsäure und wasserlöslichen Phosphaten besteht.

6. TiO₂-Katalysatorstruktur für katalytische Prozesse gemäß einem der Ansprüche 1 bis 3, wobei auf die Oberfläche der TiO₂-Katalysatorstruktur aktive Substanzen aufgebracht sind.

7. TiO₂-Katalysatorstruktur für katalytische Prozesse gemäß Anspruch 6, wobei die aktiven Substanzen ausgewählt sind aus der Gruppe, die aus Silber, Kupfer, Gold, Platinmetallen, Nickel, Molybdän und Metalloxiden mit Ausnahme von Alkalimetalloxiden besteht.

8. Verfahren zum Herstellen der TiO₂-Katalysatorstruktur für katalytische Prozesse gemäß Anspruch 1 oder 2, mit:

Herstellen einer Titanhydrat-Paste durch Hydrolyse von Titanoxysulfat;

Zufügen einer Phosphorverbindung in einer Menge, die 0,05 bis 5 Gew.-% auf TiO₂-Basis entspricht, zum Erhalten eines Zwischenprodukts; und

Trocknen und danach Kalzinieren des Zwischenprodukts für 1 bis 24 Stunden im Temperaturbereich von 350°C bis 900°C bzw. 450°C bis 800°C.

9. Verfahren zum Herstellen der TiO₂-Katalysatorstruktur für katalytische Prozesse gemäß Anspruch 3, mit:

Herstellen einer Titanhydrat-Paste durch Hydrolyse von Titanoxysulfat;

Zufügen einer Phosphorverbindung in einer Menge, die 0,05 bis 5 Gew.-% auf TiO₂-Basis entspricht, zum Erhalten eines Zwischenprodukts; und

Trocknen und danach Kalzinieren des Zwischenprodukts für 1 bis 24 Stunden im Temperaturbereich von 500°C bis 1000°C.

10. Verfahren nach Anspruch 8 oder 9, wobei die Phosphorverbindung ausgewählt ist aus der Gruppe, die aus Phosphorsäure und wasserlöslichen Phosphaten besteht.

11. Verfahren nach einem der Ansprüche 8 bis 10, wobei auf die Oberfläche der TiO₂-Katalysatorstruktur aktive Substanzen aufgebracht sind.

12. Verfahren nach einem der Ansprüche 8 bis 11, wobei ein Pulver der erhaltenen TiO₂-Katalysatorstruktur, bzw. die Katalysatorstruktur mit den aktiven Substanzen, durch Pressen, Granulieren, Pelletisieren, Flaking, Mikronisieren oder eine andere Technologie weiter in die benötigte Gestalt gebracht wird.

13. Verwendung der TiO₂-Katalysatorstruktur gemäß einem der Ansprüche 1, 2 und 6 für lang andauernde Anwendungen bei Temperaturen bis zu 800°C.

14. Verwendung der TiO₂-Katalysatorstruktur gemäß Anspruch 3 oder 6 für nur kurz andauernde Anwendungen bei Temperaturen bis zu 1000°C.

15. Verwendung gemäß Anspruch 13 oder 14, für die katalytische Zersetzung von Stickoxiden, NOx, aus Dieselmotoren und Abgasen.

16. Verwendung der TiO₂-Katalysatorstruktur gemäß einem der Ansprüche 1 bis 7 für photokatalytische Anwendungen.

Revendications

1. Structure de catalyseur au TiO₂ pour les procédés catalytiques aux températures allant jusqu'à 800 °C sous une forme de poudre consistant en des nanoparticules de TiO₂ sous la forme cristalline d'anatase dopées avec du phosphore, dans laquelle la teneur en phosphore est de 0,05 à 5 % en poids sur la base du TiO₂, et les nanoparticules sous la forme cristalline d'anatase sont organisées en les agrégats planaires circulaires ayant la surface spécifique de 40 à 120 m²/g, dans laquelle la structure de catalyseur au TiO₂ consistant en des nanoparticules de TiO₂ est préparée par le séchage et la calcination du produit intermédiaire dans la plage de températures allant de 350 à 900 °C pendant 1 à 24 heures, dans laquelle le produit intermédiaire est préparé par l'ajout d'un composé phosphoré correspondant à 0,05 à 5 % en poids de phosphore sur la base du TiO₂ à la pâte d'hydrate de titane préparée par l'hydrolyse de l'oxysulfate de titane.

2. Structure de catalyseur au TiO₂ pour les procédés catalytiques aux températures allant jusqu'à 800 °C, selon la revendication 1, consistant en des nanoparticules de TiO₂ préparées par le séchage et la calcination du produit intermédiaire dans la plage de températures allant de 450 à 800 °C pendant 1 à 24 heures.

3. Structure de catalyseur au TiO₂ pour les procédés catalytiques aux températures allant jusqu'à 1 000 °C sous une forme de poudre consistant en des nanoparticules de TiO₂ sous la forme cristalline d'anatase dopées avec du phosphore, dans laquelle la teneur en phosphore est de 0,05 à 5 % en poids sur la base du TiO₂, et les nanoparticules sous la forme cristalline d'anatase avec la morphologie de particules compactes agrégées ayant la surface spécifique allant de 20 à 40 m²/g, dans laquelle la structure de catalyseur au TiO₂ consistant en des nanoparticules de TiO₂ est préparée par le séchage et la calcination du produit intermédiaire dans la plage de températures allant de 500 à 1 000 °C pendant 1 à 24 heures, dans laquelle le produit intermédiaire est préparé par l'ajout d'un composé phosphoré correspondant à 0,05 à 5 % en poids de phosphore sur la base du TiO₂ à la pâte d'hydrate de titane préparée par l'hydrolyse de l'oxysulfate de titane.

4. Structure de catalyseur au TiO₂ selon l'une des revendications 1 à 3, consistant en des nanoparticules de TiO₂ sous la forme cristalline d'anatase, dopées avec une quantité de 0,55 à 5 % en poids de phosphore sur la base du TiO₂.

5. Structure de catalyseur au TiO₂ pour les procédés catalytiques selon l'une des revendications 1 à 3, dans laquelle le composé phosphoré est sélectionné dans le groupe consistant en l'acide phosphorique et les phosphates hydrosolubles.

6. Structure de catalyseur au TiO₂ pour les procédés catalytiques selon l'une des revendications 1 à 3, dans laquelle des substances actives sont appliquées sur la surface de la structure de catalyseur au TiO₂.

7. Structure de catalyseur au TiO₂ pour les procédés catalytiques selon la revendication 6, dans laquelle les substances actives sont sélectionnées dans le groupe consistant en l'argent, le cuivre, l'or, les métaux de platine, le nickel, le molybdène et les oxydes métalliques à l'exception des oxydes de métaux alcalins.

8. Procédé de fabrication de la structure de catalyseur au TiO₂ pour les procédés catalytiques selon la revendication 1 ou 2, comprenant :

la préparation d'une pâte d'hydrate de titane par l'hydrolyse de l'oxysulfate de titane ;

l'ajout d'un composé phosphoré en une quantité correspondant à 0,05 à 5 % en poids sur la base du TiO₂, pour obtenir un produit intermédiaire ; et

le séchage et ensuite la calcination du produit intermédiaire pendant 1 à 24 heures dans la plage de températures allant de 350 °C à 900 °C ou de 450 °C à 800 °C.

9. Procédé de fabrication de la structure de catalyseur au TiO₂ pour procédés catalytiques selon la revendication 3, comprenant :

la préparation d'une pâte d'hydrate de titane par l'hydrolyse de l'oxysulfate de titane ;

l'ajout d'un composé phosphoré en une quantité correspondant à 0,05 à 5 % en poids sur la base du TiO₂, pour obtenir un produit intermédiaire ; et

le séchage et ensuite la calcination du produit intermédiaire pendant 1 à 24 heures dans la plage de températures allant de 500 °C à 1 000 °C.

10. Procédé selon la revendication 8 ou 9, dans lequel le composé phosphoré est sélectionné dans le groupe consistant en l'acide phosphorique et les phosphates hydrosolubles.

11. Procédé selon l'une des revendications 8 à 10, dans lequel des substances actives sont appliquées sur la surface de la structure de catalyseur au TiO₂.

12. Procédé selon l'une des revendications 8 à 11, dans lequel une poudre de la structure de catalyseur au TiO₂ obtenue, ou la structure de catalyseur avec les substances actives, est davantage transformée en la forme requise par pressage, granulation, pelletisation, floconnisation, micronisation ou par une autre technique courante.

13. Utilisation de la structure de catalyseur au TiO₂ selon l'une des revendications 1, 2 et 6 pour des applications à long terme aux températures allant jusqu'à 800 °C.

14. Utilisation de la structure de catalyseur au TiO₂ selon les revendications 3 ou 6 uniquement pour des applications à court terme aux températures allant jusqu'à 1 000 °C.

15. Utilisation selon la revendication 13 ou 14, pour la décomposition catalytique des oxydes d'azote NOx à partir d'agrégats de diesel et de gaz d'échappement.

16. Utilisation de la structure de catalyseur au TiO₂ selon l'une des revendications 1 à 7 pour des applications photocatalytiques.

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